I drew (not perfectly aligned, mind you, but pretty damn close) a perfect rectangle around the card to help with the trimmed/not trimmed argument...
1951bowmanmantlerectangle.jpg
I took some of the "it's trimmed" claims to be directed at the right side not being straight and correctly oriented, but the card does seem to be a perfect rectangle. Do with that what you may. The bowing of the lower left corner area could mean the card isn't sitting perfectly flat??